The Physiologic Effects of Seat Back Angles < 45 Deg (From the Vertical) Relative to G.

摘要

Seat back angles of 13 deg, 18 deg, and 30 deg from the vertical are found respectively in the F-15, YF-17, and YF-16 fighter aircraft. Theoretically, the reasons for the departure from the standard 13 deg seat by the YF-16 and 17 are increases in pilot comfort, target visibility, performance, and G tolerance. The following objective and subjective physiologic parameters were examined relative to seat back angles of 23 deg, 28 deg, and 40 deg (seat angle +10 deg angle of attack); heart rate and rhythm; arterial oxygen saturation; performance; intrathoracic (esophageal) pressure; arterial pressure; and, subject evaluation of comfort, effort, and fatigue. Eight experimental subjects from the USAF School of Aerospace Medicine (SAM) and four YF-16/17 test pilots were exposed to a simulated aerial combat maneuver (SACM) which included 12 s of 8 G. Relaxed and straining high sustained G (HSG) tolerances (6 G for 60 s) were also determined using only SAM subjects. The advantages of the 30 deg seatback angle during the SACM included increased subject comfort, less fatigue and effort, a statistically significant reduction in the increased mean heart rate associated with G exposure, and greater pilot acceptance. On the other hand, a statistically significant reduction in arterial oxygen saturation was found during the SACM at 40 deg compared with the 23 deg back angle although this seat back angle difference was not found during the HSG exposures. An increase in relaxed G tolerance was found with the 40 deg seat back angle--statistically significant only compared with the 28 deg seatback angle.